I would look into ductless ac/heater units. They are on ebay and they have a outside unit that runs into a hotel looking unit. Make sure you get installed right and a good brand (eBay was just for reference) Its how I'm doing my rv/bus so I don't have any units or holes in my roof. Cheers

Cheap way to go is propane RV type furnace. At 35,000btu, that's more then enough for heating. Suburban makes one that has a remote outside vent that is only 3 x 6" and can be chrome. Atwood makes a good one too, but it has a large outside door since it is mounted and serviced from the outside. If mounted in the baggage compartment, just have to make a box for the furnace so to get the air from inside-rather then heating the cold baggage air. My first Atwood furnace went 18 years-until I left it on for 2 weeks. I could have just replaced the fan motor, but Atwood had made a newer type fan that is quieter-hence I replaced it. You should be able to setup the entire system for under $1,000.00. Good Luck, TomC